Haemoglobin levels in the blood

Haemoglobin carries oxygen and if it's low we're supposed to be anaemic. Older people often have haemoglobins which don't quite qualify as anaemia and doctors don't do anything about it. A study at Johns Hopkins University in Baltimore has investigated a thousand women aged over 65 and suggests otherwise. They found that within the normal range of haemoglobin there was a remarkable difference in the levels of disability.

Transcript

Now just as people should no longer accept mild declines in thinking ability, there is growing evidence that doctors have been too complacent about something else. The haemoglobin level in the blood. Haemoglobin carries oxygen and if it's low we're said to be anaemic.

Older people often have haemoglobins which don't quite qualify as anaemia or are just on the low side and no-one does anything about it.

Well a study at Johns Hopkins University in Baltimore, which investigated 1000 women aged over 65, suggests otherwise.

What they found was that within the normal range of haemoglobin, between 12 and say, 15, there was a remarkable difference in the levels of disability. Dr Paulo Chaves was one of the researchers.

Paulo Chaves: The risk goes down as you increase from low normal levels, like 12, to 14. So for the example, the level of mobility disability with a haemoglobin of 14 is half of the risk of those who have 12.

Norman Swan: Half?

Paulo Chaves: Exactly. Even taking into account all the existing diseases and all the other existing physical problems.

Norman Swan: What were you measuring with this mobility disability, tell me what was happening in real life to these people.

Paulo Chaves: They have a difficulty walking a quarter of a mile, they have difficulty climbing up stairs.

Norman Swan: And the reasoning behind that is that's when your oxygen carrying capacity is tested, and therefore if it's down a bit you may find yourself getting breathless.

Paulo Chaves: Exactly. The importance of this definition of mobility disability is not because you're not going to be able to run a marathon, but the daily activities.

Norman Swan: So what happens when somebody's got a haemoglobin of 10, say?

Paulo Chaves: People who have haemoglobin of 10 have more than 2.5 times increased risk of having disability as compared to the normal level of 12. And what we notice from other studies is approximately 30% to 40% of all adults reduce their activities. For example, they cut how often they walk. They know that they are doing that.

Norman Swan: But they don't know why?

Paulo Chaves: Exactly. And they don't perceive this as a difficulty. So you ask 'Do you have difficulty?' 'No, we don't'. The haemoglobin concentration is possibly related to this decrease in physical activity.

Norman Swan: What about other things like thinking abilities, or even at its most extreme, the chances of dying? Because there have been some studies that suggest that anaemia for whatever reason is linked to your chances of dying in the next five years.

Paulo Chaves: We also did another study that started looking at this, and we saw that again, that mild anaemia may play a causal role in terms of reducing older adults' ability to perform these tasks, which show that the 3 and the 5 year of all-cause mortality is substantially increased.

Norman Swan: Are you saying that you eliminated all those causes and you're left with just people with anaemia with no known cause?

Paulo Chaves: Yes, that's exactly what we trialled.

Norman Swan: You're saying then that you're convinced, that the haemoglobin by itself has an influence. Now if that's true, then raising the haemoglobin by giving iron or blood transfusions or whatever, might reverse this process?

Paulo Chaves: That's exactly the hypothesis that we are working on right now. If we increase the haemoglobin levels, the risk of developing mobility difficulty as well as dying, would be decreased. We don't know that for sure till we do this clinical trial, but it is a possibility.

Norman Swan: Dr Paulo Chaves is in the Center on Ageing and Health at Johns Hopkins School of Medicine in Baltimore.

Refererence:

Chaves PH et al. Looking at the relationship between haemoglobin concentration and prevalent mobility difficulty in older women. Shjould the criteria used to define anaemia in older people be re-evaluated? Journal of the American Geriatric Society. 2002;50:1257-1264

Guests

Dr Paulo Chaves

Center on Aging and Health Johns Hopkins School of Medicine Baltimore,Maryland U.S.A.